Cavitation is an undesirable condition that often occurs in external involute gear-style oil pumps that are commonly used on internal combustion engines. Cavitation occurs when the static pressure at any point in the fluid flow of the fluid being pumped becomes less than the fluid's vapor pressure, thereby creating vapor bubbles in the inlet fluid stream. When this situation arises in an oil pump, vapor bubbles in the inlet oil stream reach the high-pressure side or outlet side of the oil pump and implode, thereby causing noise, vibration, and damage to any surface of the oil pump in which the imploding bubbles touch. The effects of cavitation can range from a loss of oil pump efficiency, a reduction in the oil pumps' output, or more serious effects, such as noise, vibration, and damage to the oil pump's components.
The onset of cavitation is determined by the oil pump's speed, capacity, and inlet design. In addition, external involute gear-style oil pumps tend to cavitate at relatively low operating speeds as compared to other pump designs. Cavitation has caused lubrication issues with many high-performance engines, since many of those engines utilize an external involute gear-style oil pump. Because of this condition, many high-performance engines utilize a dry sump oiling system; however, such dry sump oiling systems are more expensive and complex, thereby increasing the cost and maintenance of such systems.